I'm restoring a 1960's (I think) 14" Woodfast. I've had it for 20 years and slowly the tyres started to fall apart so I have decided to replace them. I've removed what I am assuming is vulcanised rubber which has exposed the alloy which the tyre beds onto - there is a set of parallel ridges running around the alloy wheel which collectively gives it a very pronounced domed profile. The rubber was pretty thick too - guessing 1/4". So I bought some urethane tyres (blue ones) and I am having all sorts of problems keeping the blades on - they seem so sensitive to rolling off and I've even had the lower tyre come off. So I am thinking that maybe the domed profile is too aggressive for urethane? So I'm after some advice please. Thank you. Mick